A hole-filling process is a process where a specific material is injected into a substrate in a manner of vacuum, rolling pressure or scraping pressure. The application fields of the hole-filling process include printed circuit board (PCB, Printed Circuit Board) and surface mounted technology (SMT, Surface Mounted Technology) thereof, as well as solar electrodes, etc. With the characteristics of easy realization and low cost, the hole-filling process has become one of the most common processes of filling holes and pits.
Currently, a mature hole-filling process for a substrate surface is mainly realized through two ways: one is a screen printing method, where a wire mesh screen or a steel mesh screen is laid on a substrate, a material is coated on the screen by rolling or scraping, and the hole-filling material selectively contacts pits through mesh holes; and the other is a rolling-coating hole-filling method, where a rolling-coating wheel directly coats the hole-filling material on the substrate, so as to achieve the purpose of hole filling.
When a common hole-filling apparatus adopts the above two hole-filling processes to carry out the hole-filling operation on the substrate, generally, only a single-surface hole-filling operation can be carried out. If a double-surface hole-filling operation is carried out, the substrate needs to be manually turned over after the hole-filling operation of one surface is completed, so as to carry out the hole-filling operation on the other surface. Such hole-filling apparatus has low degree of automation, thus having low production efficiency.